1. Field of the Invention
This invention relates to an external connecting interface for computer peripheral devices and particularly to a connecting interface that can convert the IDE, SCSI, Serial Port or Parallel Port interface in a computer for connecting external peripheral devices.
2. Description of the Prior Art
Computer is now being widely used in almost all types of business, families and people around the world. In addition to data and word processing, computer function now combines communication and computing capabilities for processing multimedia function which includes words, sound and images, and is able to communicate with many other people locally or remotely. Multimedia applications usually need a powerful CPU and huge capacity of data storage devices such as CD-ROM device, high capacity hard disk or optical disk drive. In order to manage this constant need of increasing information capacity, a user either has to upgrade the hardwares or to add more capacity needed externally. To add more capacity externally is generally more flexible and convenient. Most computers now use SCSI or IDE as data interface for connecting peripherals, either internally or externally. IDE interface is generally more popular than SCSI interface.
Conventional methods for connecting computer peripheral devices such as external hard disk or CD-ROM usually use an external box or casing to contain the device, then use a cable to connect with the parallel port of the computer. Such connecting method has high portability and is easy to use. The parallel part is a standard interface for personal computer, and therefore is widely used.
However it also has the following disadvantages:
1. The parallel port interface is a low speed transmission interface generally used for connecting low speed peripheral devices such as printer. It is much slower than IDE interface and hence is not desirable for transmitting high speed information. Moreover parallel port interface has high probability of causing data loss when transmitting great amount of data.
2. In order to use parallel port interface for data transmission, a special driving program is needed to communicate with the computer since the connected external computer peripheral devices usually use IDE or SCSI interfaces. It is not convenient as not every user knows how to install the driving program. The driving program also will occupy some main memory. In some circumstance such as the computer is running under DOS operation system, it could result in insufficient memory or memory allocation error or conflict.
3. To use parallel port interface for data transmission needs a special hardware for transforming data signals between IDE/SCSI interface and Parallel Port interface. All external connecting devices require a special IC for this job. It is thus more expensive.
4. The external connecting devices also need a separate power supply. The power of the computer cannot be shared by the connected external devices. It becomes heavier and costs higher. In addition, it is not always convenient to find an additional power source for the external devices, especially when the external devices are connected with notebooks (e.g. portable computers) which are very likely to be operated and used at a place where is no electricity socket or additional power source available.